DD158900A1 - PROCESS FOR PREPARING LOWER N-ARYL CARBAMIDESTERES - Google Patents

Abstract

The invention relates to a process for the preparation of lower N-Arylcarbamidsaeure alkyl esters (alkyl = methyl to propyl), which are required as intermediates, herbicides and germ inhibitors. The invention has for its object to make the principle known production of N-Arylcarbamidsaeureester from urea, anilines and alcohols so that they can perform especially easier for the lower esters than the previously known methods and comparatively better yields. In the process according to the invention, the reaction is carried out without pressure in inert solvents having a boiling point above 140 ° C., the alcohol being added in the amount consumed by the reaction. In order to reduce the N.N'-diarylurea fraction which is by-produced in the reaction, further alcohol is subsequently added and the reaction time is prolonged. The yields of carbamates can be increased by up to 20% and are at 70 to 80% d. Th. (Relative to aniline).

Description

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In the third place:

Process for the preparation of lower ϊΤ-aryl-carbamide acid esters

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and

Manufacturing * of ~ χ srti siele ""'«ICei ™ * ·

Characteristic of the "bakamitsn teclinischen Lösun.ireiii

iM-r "i-carc8j ~! iLaso.urees ~ 3r 3-stst; man

For the production

Aryli'so cyanate e

bring in the end, if you end up on phosgene:

Arvli'soC "anate or Arylcaroamidsäurechlorids with Aiko

/) - ^MA 2

CCGL,

NGO 4- 2HCl

Although these reactions are very smooth, a Srsats the phosgenation process is sought for the following reasons:

Phosgene is corrosive and extremely toxic. 3s is gaseous at llormaltemperatur, so it must be stored under pressure · phosgene contains 71.5 > unproductive chlorine, which plays only a ballast role and is recovered as hydrochloric acid «In order to circumvent the use of phosgene, other technical reading paths have been proposed. Thus, according to a recent development direction, it is possible to prepare IT arylcarbamic acid esters by reacting aromatic nitro compounds with CO under pressure and in the presence of alcohol and various catalysts, such as hexelmetals or selenium:

+ 3CO + ROH -> · 4 Λ-HH-C-OR + 2CO

The introduction of these methods still poses technical difficulties and high catalog costs in the future *

On the other hand, it has long been known that urea and alcohols can simply be produced by the preparation of substituted carbamic esters, with ammonia cleaved off:

H ₀ IM-C-IiIH ₀ + ROH -S » H ₀ HC-OR + 2IH.

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To accelerate the reaction, catalysts are added, such as cobalt chloride, copper or sink acetate. ileistens reaction temperatures above 130 ⁰ C are required, so that one must usually work under pressure to obtain the lower carbamates (R = -CH ^ ₅ to -C ^ H "). the fact that the ammonia formed can not escape from the reaction mixture adversely affects the reaction.

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In IJSP 3 013 O65, therefore, "special procedures and devices have been described for separating the resulting gases from the Aikoho steam by condensation and returning the latter to the pressure vessel." Further, U.S. Patent 2,837,561 also discloses a non-pressurized operation been mentioned, wherein the lower alcohols in the liasse in a urea melt to be entered, as the reaction proceeds and releasing ammonia · 3 ¹ Ur, however, this operation is only 41% yields of O-methyl or O-60% jSthylcarbamat while the higher alcohols are accessible with better yields.

In principle, it is also possible to prepare the IT-arylcarbamic acid esters from arylhaimns and alcohols (equation I) or from anilines by simultaneous reaction with urea and alcohols. (Equation II)

/ R-2.

In addition, however, there are other xieaktionsmöglichkeiten given. so that from the outset with a considerable amount of competition reactions is expected. The practical implementation of these reactions actually produces extremely unsatisfactory results in many cases. In US Pat. No. 2,010,051, only economically viable yields have been described for n-butyl Π-phenylcarbamate. The particularly interesting for practical application iT aryl carbamic acid esters of lower alcohols (R = -GH ₀ to -C ₀ Hr ₇ ) are on this Wese either only in minimal yields (7 % for IsoproOvlester) or über-

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has not yet been won, which is obviously due to the difficulties in transferring the methods practiced so far ·

Zdel of invention:

The aim of the invention is to find a method for the preparation of lower N-aryl-carbamic acid esters, which starts from the abundant and inexpensive available urea, can be performed simpler than the methods previously used on this basis and provides comparatively better yields.

Explanation of the essence of the invention:

When Xonzipierung the desired manufacturing method for lower IT-aryl-caroamic acid ester was deliberately omitted from a pressure reaction, because this work orphan is associated with a significantly increased equipment costs »The orientation to a non-pressurized process appeared in the prior art, although in principle feasible, However, in comparison to the 17-unsubstituted carbamates, no useful austenite could be expected. Apart from the fact that the addition of low-boiling alcohols to a much higher tempered melt poses technical problems, material difficulties were foreseeable. These were already deduced from the known fact that the H-aryl ureas to be used or intermediately decompose on melting or heating to higher temperatures with disproportionation and formation of H.iT'-Diarylharnstofxen.

However, it was surprisingly found that "relatively favorable results can be obtained when the reaction is carried out in an inert, high boiling solvent. Ais high boiling inert solvent whose boiling point should not be below 140 ⁰ G, hydrocarbons, halogenated hydrocarbons, Diglycolether- Phenol ethers, ITitrobenzen and other types of compounds into consideration.

The particular signing needs to be reviewed on a case by case basis and can affect the execution and results. Thus, for example, the decalin is hardly suitable because of poorer Löseeigenschaften in contrast to tetralin. Of the chlorohydrocarbons, for example, the dichlorobenzene and chlorotoluene, from the phenol ethers: the anisole is used "

For the application of .findfindungsgemäßen process can both H-phenylurea and alkanols (R = CH-, to C ^ H ₇ ) is assumed (equation DaIs also the direct preparation of urea, anilines and the respective alcohol are chosen (equation II).

The reaction temperature should be above 130 ⁰ C, preferably at 140 - 160 ° Cj. For this purpose, therefore, one adds the alcohol at such a rate as it is consumed and the said temperature can be maintained in the reaction container ar. The workup of the reaction mixture depends on the type and the bipolar:

She can at

In the case of crystallization, the mother liquor is expediently recirculated, which reduces the expense and leads to increased yields in the subsequent batches The recovered high-boiling solvent can be used as often as desired, provided enrichment of interfering impurities is avoided. "

naturally the application of the process according to the invention can not completely avoid the general competing reaction of IT.Ii'-diarylurea formation, but can only be kept within limits. The reaction products thus contain certain proportions of iT.H'-diarylureas, but are difficult to solubilize or by distilling off the carbamate can be separated.

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Depending on the use of the carbamate, such separation steps can already be taken into consideration during the process. The resulting in such a separation IuIP-diarylurea can find another use or be worked up in a conventional manner. It is expedient, however, to minimize the attack from the outset. Surprisingly, it was found that the Diphenylhanistoffanteil push back considerably and thus the yield of Garbaniaten can increase up to 20 % , if you extend the reaction time with gleichseitiger alcohol addition »Thus, the ll-Phenylcarbamidsäuremethylester at 16 hr. Reaction time with a yield of 56 % , which increases to To, 5 %> when the reaction time reaches 24 3td. is extended. ' Similarly, the conditions in the production of isopropyl (II-phenylcarbamate) (IPC): Bei 10 hour reaction time, IPC is obtained in a yield of 54 % of theory with a total accumulation of 21% by weight of diphenylurea corresponding to 24 * 4 % of the amount of aniline employed. Reaction time increases the yield to T2, 5 / S d.'I'h ·, the Dipheny! Urea content goes back. The reason for increasing the yield over a relatively long reaction time is evidently a reaction of the carbamic acid ester formed as a by-product from urea and alcohol with the diphenylurea to give the desired 1-methylphenic acid ester. If one proceeds under otherwise similar reaction conditions instead of aniline and urea of phenylurea (Example 5) »only an IPC yield of 60.1, S is achieved at a DPH attack of 15.0 wt .- / S = 15j7 - -Io 1; · 'ί, based on phenylurea used ff.

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Instruction:

The process of the invention is illustrated by the following examples, wherein the figures contained therein are not to be considered as optimum:

Example 1: IT-phenylcarbarnid acid methyl ester

In a sulphonation flask equipped with stirrer, reflux condenser with gas discharge tube, thermometer and dropping funnel are added 3 g of urea (0.6 Hol), 46.57 g of aniline (0.5 g / l) and 1 g of zinc acetate in 100 ml of o-chloroformate When the internal temperature of 155 g is reached, 17 g of methanol (0.53 l) are slowly added dropwise so that the internal temperature does not drop below 150 g after about 7 h. the methanol has been added ., an additional 17 hours be boiled at reflux, by further Hethanolsugabe the boiling temperature between 150- - wiz'ö held i50 '~ Ό Ii then wiro i * ~~ · the IiGsuii ~ s iiitt3l * estilliert> ?, and? distilling the carbamate,

Kp. .., _r " _ba " 110-115 ⁰ G, yield 60.7 g = SO.3 ΐ * d.Th .; '3 ¹ P, 43 """- ¹ ^ ⁰ G.

Example 2: H-Phenylcaroamic acid ethyl ester

Analogously to Example 1; Total reaction time 24 h, yield 66, Og = 79.9 % of theory, Pp / 46 .- 47 ⁰ G.

Example 3 H-phenylcarbamic acid isopropyl ester (IPC)

In the manner described in Example 1 Apparatus v / ground 36 g of urea (0.6 mole), 49.7 g of aniline (0.53 Hol) and 1 g of zinc acetate in 100 ml of o-üichlcrbenzen and treated at 150 - ⁰ T60 G internal temperature 36 g of isopropanol (0.6 Hol) added dropwise after 3 hours. Is the addition complete? it is then kept at the same temperature for a further 16 hours with further isopropanol (approximately 15 ml), then the solvent is distilled off with steam and the residue is stirred with 280 ml of methanol.

The undissolved Dipheny! Urea (2.17 g) is filtered off, and the IPC is precipitated from the filtrate with 280 ml of water. This gives 71.5 g = 72.5 % of theory (taking into account a diphenic acid content of 3.times.3% ₉ determined by FAO method ITr.30 in FAO Plant Product Bull. Y (1965), 33) 3 ¹ P. 76 - 81 ⁰ C.

Example 4: -I- (3- ^G- chlorophenyl) -carbamic acid isopropyl ester (CIPG)

As described in Example 1, 63.3 % m-chloroaniline (0.5 Hol), 3c g urea (0.6 KoI) and 36 g of isopropanol (0.6 Hol) in the presence of 1 g of zinc acetate in 100 ml o Dichlorobenzen'bei 15O - I60 ⁰ C reacted together. The addition of the isopropanol lasts about 3 seconds, then the reaction mixture is refluxed for 17 hours at the same temperature under a further addition of isopropanol (about 10 ml). The solvent is removed by steam distillation, then the residue i.y distilled ^K p4 a ba- ¹⁴³ - ¹⁵ ° ^C > ^A yield 74.4 g = 69.4 ρ d.h.h, I ¹ P. 30 ^ 32 ⁰ C.

Example 5 · H-phenylcarbamide sarse isopropyl ester (IPC)

63 g of phenylurea (0.5 mol) and 1 g of zinc acetate are heated in 100 ml of o-dichlorobenzene to about 155 ° ^G ; then allowed to drop 36 g of isopropanol (0.6 Mo!) With the speed drop that the internal temperature does not fall below 145 ⁰ C. After about 15 hours, the addition is complete, the approach is another 5 3td. held at this temperature and worked up as described in Example 3. 6.8 g diphenylurea be filtered from the methanol solution · On the addition of water 1 70 d.I'h obtained 55.3 = 60. (taking into account a DPIi content of 2.7 %) * mp 81-84 ⁰ C.

Claims (2)

c 'IDrefindungsansprüche: 1, Process for the preparation of lower ίί-Arylcarbamidse, ure ~ aikylestern the general formula Arvl-ITH-C-OR (R = -CH _n to -CH ₇ ) by reaction of Il " ^{3 T} O " if necessary, aniliate, urea and alkanols (GH ^ ₁ OH "to C-jH ₇ OH) or by reaction of Ϊΐ-arylurea (Iryl.-UK-GO-NH _? ) with alkanols (CH ₃ OH to G ₇ H ₇ OH), characterized in that the reaction is carried out without pressure at a temperature above I30 ⁰ G in indifferent solvents having a boiling point above HO ⁰ C at oimal pressure and thereby adding the alcohol in your HaSe, as he by the reaction consumes vrird, 2 «method according to claim '!, characterized in that: na.n to reduce the costs incurred in the implementation as ITaoenprocukt IT 27 ⁷ -Diarvlharn2to ff -Anteils further alcohol and prolongs the reaction time.